Ionization Energy

Ionization energy is the term used in chemistry. Ionization Energy Define- It is defined as the energy needed to remove an electron from an atom. It is obvious that after the removal of electron, atom will be converted into positively charged ion. Also one thing that should be noted is that we can remove electron from the outermost shell of the atom only.

After removal of one electron from the atom and then removing one more electron from it, the energy required to remove it will be more than that required when the first electron was removed. Similarly when we remove third electron from that ionized atom, the energy required will be more than that required while removing the second electron.

Energy required when removing the outermost first electron is known as first ionization energy Charge on the atom after remove of one electron will be +1. Removing electron from +1 charged atom will require an energy known as second ionization energy Generalizing this, we can say that the energy required to remove an electron from atom of charge +(n-1) .

First ionization energy =>X → X + + e-

Second ionization energy =>X + → X 2+ + e-

Third ionization energy => X 2+ → X 3+ + e-

Nth ionization energy =>X n+ → X (n-1) + + e-

Note that nth ionization energy will always be less than (n-1)th ionization energy This is because in a charged atom, the positive charge is more and orbital in the atom come closer after electron removal. This increases the electrostatic force of attraction among the electrons and hence it becomes more difficult to remove electron from positively charged atom. Hence more energy is needed thereby increasing the ionization energy.

Units of ionization energy vary. In chemistry it is measured per mole of a substance and is given as Kilo joules per mole or kilo calorie per mole.

Let us see all Factors Affecting Ionization Potential of an atom. These are mainly atomic size, nuclear size, shielding effect or inner electrons of the atom.

Large size of atoms reduces the ionization energy of the atom. Higher charge inside the nucleus increases the ionization energy The ionization potential is higher for completely or partially filled outermost shell as these are more stable as compared to other shells.

Ionization Energy Equation for an electron to leave an atom is given as;

E = - (Z2 * 13.6eV)/n2Z is number of protons in the nucleus; n is no. of orbits.

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